Trans fatty acids: are we talking about them again?
Trans fatty acids of industrial origin (see insert) are back in the news.
Following the launch of a campaign by the World Health Organisation in May 2018 to eliminate industrially produced trans fatty acids in food[1], the European Union recently adopted a regulation on the limitation of industrially produced trans fatty acids. The regulation, which will come into force in May 2019, specifies that the content of trans fatty acids other than naturally occurring trans fatty acids should not exceed 2 grams per 100 grams of fat in foodstuffs intended for the final consumer and for retail sale[2].
What is the purpose of limiting trans fatty acids?
Observational and cohort epidemiological studies show that consumption of total trans fatty acids[3 ] and industrially produced trans fatty acids at high levels significantly increases the risk of cardiovascular disease. Hence the importance of limiting their consumption.
However, this is not a new issue, as it was already the subject of recommendations in France in the early 2000s. The French Food Safety Agency (now the Anses) recommended limiting the consumption of total trans fatty acids to a maximum of 2% of total energy intake (i.e. 4.4 g/day)[4]. Recommendations were also made to industry to limit the content of total trans fatty acids in different product categories.
The "Aquitaine" study[5] conducted by ITERG at the end of the 1990s showed that the average consumption level of trans fatty acids was 2.7 g/day per person (i.e. 1.3% of total energy intake) and that it had no impact on cardiovascular risk. Further work by ITERG on a biomarker of consumption (fatty acid content of breast milk) has demonstrated a decrease in the consumption of these trans fatty acids in France over the period 1997-2014 (-51% trans fatty acids in breast milk)[6].
What about the vegetable fats consumed in France?
In France, partially hydrogenated oils, which are sources of trans fatty acids, are mainly used for frying foods and as ingredients in bakery products, in most biscuits, chocolate bars, spreads or pastries sold in supermarkets.
On the other hand, the vegetable oils on our shelves, such as sunflower, rapeseed, olive, walnut and other oils, do not use hydrogenation; they are rich in monounsaturated and polyunsaturated fatty acids, which are known to have beneficial effects on cardiovascular health.
Margarines, which were often criticised in the past for being made from partially hydrogenated oils, are now completely free of trans fatty acids, as the manufacturing processes have been optimised over the last 20 years.
In summary, vegetable fats (oils and margarines) marketed in France are not affected by the trans fatty acid issue.
[1] https://www.who.int/nutrition/topics/replace-transfat
[2] https://eur-lex.europa.eu/legal-content/FR/TXT/PDF/?uri=CELEX:32019R0649&from=EN
[3] This term is the sum of naturally occurring and industrially produced trans fatty acids.
[4] https://www.anses.fr/fr/system/files/NUT-Ra-AGtrans.pdf
[5] Boué et al. 2000. Lipids 35, 561-566; Boué-Vaysse et al. 2009. OCL 16(1): 4-7
[6] Couëdelo et al. 2016 Lipid'Nutri+ n°30 http://www.terresunivia.fr/sites/default/files/Lipid%20Nutri+/ln_n30.pdf